1. Field of the Invention
This invention relates generally to a steerable antenna feed horn and, more particularly, to an antenna feed horn that employs a series of linear motion mechanical devices, such as micro-electro-mechanical systems (MEMS) or carbon nanotube artificial muscles, to selectively change the end of the feed horn into various asymmetrical configurations to redirect the beam.
2. Discussion of the Related Art
In many high gain, narrow beam communications systems, it is necessary to tightly control the beam pointing direction of a transmitting antenna so that it is accurately directed towards the receiving antenna. For example, in satellite communications systems that operate in the gigahertz frequency range and employ high gain beams, it is necessary that the ground station antenna be accurately pointed at the satellite antenna and the satellite antenna be accurately pointed at the ground reference location to ensure that the highest power portion of the beam is received at the desired location. Because satellites drift relative to the ground station, antenna direction control is necessary to adjust the pointing direction of the satellite antenna or the pointing direction of the ground station antenna to maintain an accurate pointing direction.
To perform this directional control for high gain and high frequency communications systems, it was heretofore necessary to either change the pointing direction of the entire antenna system, and/or adjust the attitude direction of the satellite relative to the ground station. This type of directional control is generally complex and costly to implement and may add significant weight to the satellite. Antenna feed horns with asymmetric openings have heretofore been known in the art to direct the beam being emitted therefrom in a certain direction. However, it would be desirable to selectively control the asymmetry of the feed horn to selectively control the beam pointing direction and reduce system complexity.
An antenna is desired in these communications systems that has a radiation pattern that can be controlled over a relatively small angle without physically moving the entire antenna or its feed, or without the use of a phased antenna array. Such an antenna directional control could be used to compensate for small alignment errors between the antenna and its mounting structure, for example, a spacecraft bus. Also, this antenna could be used in an autotrack system that requires only small angular movement, and to implement beam scanning or hopping over small offsets relative to the nominal beam location.
What is needed is an antenna system for a high gain, high frequency communication system that has tightly controlled directional movement of the antenna beam, without the need to move the entire antenna system. It is therefore an object of the present invention to provide such an antenna system.